Originally Posted by Dockhead
Are you sure that makes any difference? As far as I know, the load is not concentrated at the head of the sail -- it's spread across the luff. ....
Leech tensions are high on tall mainsails, and they appear at the masthead in the form of halyard
tension pulling downwards, and a significant aftwards force from the horizontal component of the leech vector.
That aftwards force is responsible for the automatic depowering that you get in fractional rigs, as the increasing leech tension in puffs causes the topmast to curve aft.
And in masthead rigs, the nett longitudinal force at the masthead from the vector sum of the loads in the headsail luff, the forestay and backstay, and the leech load from the main, (the considerable leech load from the genoa
or blade jib
is virtually vertical so it doesn't really come into the picture) is as much as three quarters of the lateral load at the masthead.
It's directed aft.
If the backstay adjuster
is released (or the stay fails !), as long as you're hard on the wind
and the main remains sheeted hard with plenty of breeze, the forestay tension will not be lost
, and in the case of an in-line rig, that's purely from the leech load on the mainsail